In the Wheatstone-bridge circuit shown in the original question, potentials at A and B are equal. The source is 40 V. Find the total current I.

Question

G1 Physics · Accepted Answer

Balanced bridge condition gives R/10=40/20, so R=20 Ω. With no current through the 50 Ω bridge branch, the two series branches are 10+20=30 Ω and 20+40=60 Ω in parallel. Their equivalent is 20 Ω. Thus I=40/20=2 A.